Kiwi plant named `Tomua`

ABSTRACT

A new and distinct kiwi plant of the species Actinidia deliciosa (A.Chev.) C.F. Liang et A.R. Ferguson is described. The cultivar results from a controlled pollination of A. deliciosa DA02 --  03, a male selection of unknown parentage, and the female A. deliciosa `Hayward`, the most widely grown cultivar of kiwi worldwide. Both named parents (DA02 --  03 and `Hayward`) are unpatented cultivars. The new cultivar is distinguished by its early harvest time (about 4 weeks ahead of `Hayward` in NZ), fruit appearance similar to `Hayward`, and moderate plant vigor.

BACKGROUND TO THE INVENTION

Kiwi plants in cultivation are deciduous vines of A. deliciosa. There are more than 60 species in the genus Actinidia originating in China and parts of Asia. The kiwi cultivar `Hayward`, developed in New Zealand, is the most widely grown cultivar because of its distinctive green flesh, good flavor and long storage life. Plants are dioecious, so male pollinizers are required as well as female plants to ensure fruit production.

Kiwi plants grow vigorously in spring, and rapidly develop a canopy of canes up to 6 m long if not managed correctly. Plants require a mild, warm-temperate climate, free from late spring and early autumn frosts, and need well-drained soils to produce consistent, heavy crops of fruit. Regular irrigation is necessary in dry spells. Flowering occurs in late spring (mid-late November in New Zealand). The distinctive, green-fleshed fruit develop rapidly after pollination and reach 90% of their harvest weight after 3 months. Fruit from the cultivar `Tomua` is harvested in early April in New Zealand, while `Hayward` is normally harvested during May.

SUMMARY OF THE INVENTION

The present invention relates to a new and distinctive kiwi plant having an ovoid shaped fruit. More particularly, the new cultivar is designated `Tomua`, and is derived from a controlled pollination of A. deliciosa DA02₋₋ 03, an unpatented male selection of unknown parentage, and `Hayward`, also unpatented. The male parent, which originated from seeds introduced from China in 1975, was selected as the pollen parent for the crosses because of its very early-flowering characteristics. The seed parent `Hayward` was selected for its large size, good flavor and good storage life.

The new cultivar of kiwi was created in the course of a plant breeding program which was initiated in 1983 at Hort Research in Te Puke, New Zealand. An early-flowering unpatented A. deliciosa male, DA02₋₋ 03, was crossed on to the unpatented seed parent `Hayward` by Russell Lowe in November 1983. 59 seedlings from this cross were planted out in the field in April 1986. By December 1990 most plants had flowered and `Tomua` was selected by Russell Lowe and Hinga Marsh from 19 female seedlings in this population. `Tomua` fruit matured 4 weeks ahead of `Hayward` and had acceptable fruit size, a good flavor and appeared to have commercial potential.

The new cultivar can be asexually reproduced as cuttings or by grafting or budding on to seedling or cutting-grown rootstocks of A. deliciosa. Trial plantings, established in 1989 at Te Puke, with plants grafted on to clonal `Hayward` rootstocks, have shown that the unique combination of characteristics come true to form and are established and transmitted through succeeding asexual propagations. `Tomua` flowers two weeks ahead of `Hayward`, so the usual pollinizers used for `Hayward` are ineffective. Two new and unpatented early-flowering pollinizers designated Hortkiwi `Ranger` and Hortkiwi `King` have been selected as males for use in new plantings of `Tomua`.

BRIEF DESCRIPTION OF THE ILLUSTRATIONS

FIG. 1 shows typical fruit on the vine of the cultivar `Tomua`.

FIG. 2 shows typical fruit on the cultivar `Tomua`. Note pointed stylar end.

FIG. 3 shows `Tomua` fruit in cross-section and profile.

FIG. 4 shows `Hayward` fruit in cross-section and profile.

FIG. 5 shows `Tomua` fruit in close up. Note overall similarity to `Hayward`

FIG. 6 shows `Hayward` fruit in close up.

FIG. 7 shows flowers of the cultivar `Tomua` on the vine. Note petals cupped around the ovary.

FIG. 8 shows flowers of the cultivar `Hayward` on the vine. Note petals in horizontal alignment.

FIG. 9 shows mature leaves of the `Tomua` vine.

FIG. 10 shows mature leaves of the `Hayward` vine.

Photographs of fruit on the vine were taken just prior to the harvest date. Colors may vary depending upon growing conditions under different climate, soil, and cultivation conditions and the fruit skin color may vary depending upon extent of exposure to direct sunlight.

The fruit of `Tomua` are ovoid in shape, tapering towards the stylar end, generally circular in cross-section although slightly flattened (FIG. 3). The flesh of `Tomua` fruit is medium green like `Hayward` with a columella similar to `Hayward` (FIG. 4). The hairs on the skin of the fruit of `Tomua` are slightly stiffer than those of `Hayward` and slightly prickly to the touch, but are very easily removed by rubbing or brushing to reveal a rather shiny skin (FIG. 2). The skin color of `Tomua` fruit is a reddish-brown in contrast to that of `Hayward` which is a medium brown color. `Tomua` fruit are slightly longer than those of `Hayward` for an equivalent weight. The length to (maximum) width ratio for Tomua fruit is 7:5 while that of Hayward fruit is 6:5. `Tomua` fruit have a higher dry matter content at harvest and are sweeter tasting than `Hayward` fruit when ripe. The storage life of `Tomua` fruit when held at 0° C. is about 12 weeks while that of `Hayward` is up to 25 weeks under ideal conditions.

BOTANICAL DESCRIPTION OF THE PLANT

The new cultivar `Tomua` is pistillate with imperfect flowers, i.e., only sterile pollen is produced and thus flowers require a pollinizer for fruit production. Two specific pollinizers have been developed for `Tomua` and they are named Hortkiwi `Ranger` and Hortkiwi `King`. Characteristics of the new cultivar by which it differs from the common `Hayward` cultivar include earlier flowering and harvest times, longer fruit shape, more easily removed hairs on the skin, more pointed shape at the stylar end (FIG. 2) and reddish-brown colored skin. Horticultural terminology is used in accordance with revised UPOV guidelines for kiwi.

    ______________________________________     TABLE OF CHARACTERISITCS     Characters of the `Hayward` comparison cultivar are noted in  bracket!     opposite that character only when significantly different.     All dimensions in millimeters, weights in grams.                    Tomua      Hayward     ______________________________________     PLANT     Plant: sex expression                      female     Plant: ploidy    hexaploid (2n =                      6x = 174)     Plant: vigor     medium     Young shoot: hairs                      present     Young shoot: density of                      medium     hairs     Young shoot: type of hairs                      velutinous     Young shoot: anthocyanin                      medium     coloration of growing tip     young shoot: anthocyanin                      weak     coloration of leaf axil     STEM     Stem: diameter   medium - Mean                      10.8 mm (Range                      10.2-12.3)     Stem: dormant bud diameter                      2.55 mm                      (1.7-3.1)     Stem: color on upper side                      red-brown     of shoot     Stem: hairs      present     Stem: conspicuousness of                      conspicuous     lenticels     Stem: number of lenticels                      medium     Stem: color of lenticels                      brownish-                      white     Stem: size of bud support                      medium     Stem: visibility of bud                      inconspicuous     (dormant canes)     Stem: number of hairs                      few     visible on bud     (dormant canes)     Stem: leaf scar  medium     LEAF     Leaf: general shape of                      round         very     blade                         broadly                                   ovate!     Leaf: length     140 mm                      (120-160 mm)     Leaf: width      149 mm                      (100-170 mm)     Leaf: shape of tip of blade                      mucronate     Leaf: shape of base of blade                      cordate     Leaf: arrangement of leaf                      overlapping     bases     Leaf: puckering/blistering                      medium     on upper side of blade     Leaf: margin     ciliate     Leaf: green color of upper                      medium     side of blade     Leaf: glossiness of upper                      medium     surface of blade     Leaf: color of lower side                      light     of blade         green     Leaf: glaucousness (lower                      absent     side of blade)     Leaf: petiole length                      87 mm                      (52-150 mm)     Leaf: hears on petiole                      present     Leaf: density of hairs on                      medium     petiole     Leaf: anthocyanin coloration                      weak          medium!     on upper side of petiole     FLOWER (Measurements taken     from a sample of 20 flowers)     Inflorescence: predom-                      one     inant number of flowers     Pedicel: length  medium -                      36.9 mm                      (31.0-43.0 mm)     Pedicel: hairs   present     Pedicel: length of hairs                      medium     Flower: number of sepals                      >5     Flower: color of sepals                      brown     Flower: diameter (terminal                      large -     or king flower when fully                      63.3 mm     open)            (47.8-70.6 mm)     Flower: petal length                      30.0 mm                      (25.3-34.3                      mm)     Flower: petal width                      22.7 mm                      (18.5-29.6                      mm)     Flower: petal length/                      1.33 mm     width ratio      (1.11-1.48                      mm)     Flower: mean number of                      7 (6-8)     petals per flower     Flower: number of flowers                      15 out of     with more than six petals                      20 flowers     Flower: arrangement of                      overlapping     petals     Flower: petal shoulder                      present     Flower: primary color of                      white     petals on upper side (when     fully open)     Flower: type of coloration                      uniform color,     of petals        i.e., not bi-                      colored     Flower: number of styles                      37.3 (31-43)     Flower: attitude of styles                      semi-erect     Flower: amount of hair on                      strongly     ovary            expressed     FRUIT Measurements are from     10 fruit sampes     Fruit: overall size                      medium 91 g   large!     Fruit: mean length                      73.9 mm                      (69.1-79.1                      mm)     Fruit: width (max.)                      51.56 mm                      (47.4-55.0                      mm)     Fruit: width (min.)                      44.9 mm                      42.8-47.3                      mm)     Fruit: locule number                      36.9 (33-40)     Fruit: general shape                      ovoid (tapers                      toward stylar end)     Fruit: cross-section at                      elliptical    oblate!     median     Fruit: general shape of                      raised        flat!     stylar end     Fruit: shape of shoulder                      rounded       almost     on salk end                   square!     Fruit: skin color at harvest                      reddish-      brown!     (fruit still hard)                      brown     Fruit: skin color change                      absent     during ripening     Fruit: skin color at                      reddish-      brown!     maturity for consumption                      brown     Fruit: hairs     present     Fruit: density of hairs                      medium     Fruit: type of hair                      bristly       hirsute!     Fruit: concentration of hairs                      uniform     Fruit: adherenece of hairs to                      weak          strong!     skin (when rubbed)     Fruit: core (columella)                      medium to     large!     diameter (at largest dia.)                      large     Fruit: core shape (in cross                      elliptical     section)     Fruit: core woody spike                      present     Fruit: prominence of core                      medium     woody spike     Fruit: outer pericarp color                      light green     at maturity for consumption     Fruit: inner pericarp color                      green     (locules) at maturity for     consumption     Fruit: core color at maturity                      greenish                      white     Fruit: soluble solids                      medium -     concentration SSC                      14.3%     (Brix level) at maturity                      (13.5-15.1%)     for consumption     Fruit: Vitamin C content at                      medium     harvest          (100-125 mg/                      100 g fresh                      weight)     Fruit: seed color at maturity                      dark                      brown     Fruit: seed color when dry                      brown     EVENTS (at Te Puke,     New Zealand)     Time of vegetative                      early (late     budbreak         August to first                      week of Sept.)     Time of beginning of                      medium (second)                                    two weeks     flowering        to third week                                   later!                      of Sept.)     Time of harvest at 6.2%                      medium (first                                    four weeks     SSC              weak of April)                                   later!     ______________________________________

HORTICULTURAL CHARACTERISTICS

Details below relate to observations made on plants grafted on `Hayward` clonal rootstocks (rooted cuttings) growing at Te Puke Research Centre, New Zealand.

`Tomua` vines can be grown on the same rootstocks as can `Hayward` vines. Rootstocks currently used in New Zealand include A. deliciosa seedlings, `Hayward` rooted cuttings and Hortkiwi `Kaimai`. `Tomua` can also be grown as self-rooted cutting grown plants.

In Te Puke, from 1993-1997 the `Tomua` harvest time has been consistently 4-5 weeks ahead of `Hayward` using the criteria of a Soluble Solids Concentration (SSC) of 6.2% to begin harvest.

The storage life of `Tomua` fruit is about half of that of `Hayward` fruit under cool storage temperatures of 0° C., but this is not considered a disadvantage as `Tomua` fruit can be sold before the main `Hayward` crop is harvested.

`Tomua` fruit soften more rapidly than `Hayward` fruit so the consumer can more readily obtain fruit that is in a "ready-to-eat" condition at the start of the kiwi fruit harvest season. `Tomua` fruit are sweeter tasting than `Hayward` with a tangy balance of sweetness and acidity.

Yield data: `Tomua` vines carry lower yields of Class 1 (export grade) fruit than `Hayward` when plants of equivalent ages are compared, mainly because fruit of `Tomua` are smaller on average than those of `Hayward`.

Three years of data from a replicated trial planting containing `Tomua` and `Hayward`, planted in 1989 at Te Puke is presented below in Table 1.

                  TABLE 1     ______________________________________     TOMUA AND HAYWARD YIELDS     Fruit number   Trays (3.6 kg)                                 Size (grams)     Year  Tomua   Hayward  Tomua Hayward                                         Tomua Hayward     ______________________________________     1996  938     708      23    22     92    117     1997  909     1331     23    35     93    96     1998  1149    1020     24    30     89    111     Means 999     1020     23    29     91    108     ______________________________________     Fruit flesh and skin color measurement.     RHS Colour Chart, the Royal Horticultural Society, London     ______________________________________     1966.            Flesh Color at maturity:     Outer pericarp                   138B-138D   Hayward 138B-138C!     Tomua     Fruit core:     Tomua         155-155B    Hayward 155A!     Seed color (in fruit):                   200A     Seed color (dry seed):                   165A-165B     Fruit skin at maturity:     Tomua         165B        Hayward 164B!     Leaf color: mature leaf     after petal fall     Upper side of leaf                   137A or     Tomua         147A     Lower side of leaf                   147B-147C     Tomua     Petiole color:     exposed side  178B     Flower petals:     main body     155D     base          154C-154D     Plant Stem:     exposed side: 165A     Lenticel color:                    164B-164C.     ______________________________________ 

We claim:
 1. A new and distinct kiwi plant of the species A. deliciosa substantially as described and illustrated in the specification above, characterised by early harvest date compared to `Hayward`, medium green flesh, reddish-brown skin, easily removable hairs, and a slight pointed stylar end. 